text:
Are the A320's A and B electrical buses both energized all of the time during flight?
I'm a novice reading a quick study guide.
For electric power, I notice that the A320 has two buses: A and B.
Are they both energized all of the time during flight? If not, is there a way to switch between buses?
The power diagram with the two buses looks similar to the Apollo Command Module and maybe the Service Module.  I wonder if it was a borrowed idea.

They are both energised all of the time except emergency situations. The essential devices can be switched between them, the non-essential ones will be turned off in such cases.

There is actually a couple more buses than two. The main ones, AC BUS 1 and 2¹, are powered by one engine-driven generator each, and are normally not connected. This has some advantages that

the generators don't have to be synchronized, and
if there is a short-circuit on one, the other remains functional.

The APU generator and external power are connected to a bar that can be connected to either and automatically connects to whichever is not powered. This bar can also be used for connecting the buses in case only one generator is running, and this can be controlled by a switch.
The essential devices, which means most cockpit instruments, are connected to a separate Essential AC BUS, which is normally connected to the AC BUS 1, but can be, manually, switched to AC BUS 2, in case AC BUS 1 does not work. It can also be powered by emergency generator (on RAT) or even an inverter from the batteries when RAT does not work (before it deploys and after landing during roll-out).
The even more important devices, including the flight control computers, are connected to the DC HOT BUSes directly powered by batteries.
So the essential devices can be switched when either bus is not energized. The non-essential devices like galleys, in-flight entertainment and cabin lights, will be powered off in that case. They will also be disconnected if the bus is energised, but does not have enough power (automatic load shedding).

¹ In the document I have they are not called A and B. The document document is (I got it off the internet², so it's not official copy for legal purposes) titled A318/A319/A320/A321 Flight deck and systems briefing for pilots and apparently created by Airbus (in 2007, but it's unlikely they changed this since)
² This or this is a slightly different version (even older, dated 1998), but the chapter 3. Electrical System has the same content. The included image is from the later link.

Non-essential: cabin lights. Makes perfect sense, however it raises another question. Since cabin lights are on during a landing to make evacuation easier should an issue arise, are the cabin lights powered at landing in a partial power loss situation, and, if so, where does the power come from? Feels a whole new question coming on...

@FreeMan, IIRC cabin lights are off on landing so it's easier to see outside. There are emergency lights to aid evacuation.

I started to ask that question and found a question about cabin lighting at takeoff/landing - it indicates that the interior lighting level is usually matched to the exterior lighting level, so I didn't finish asking. (i.e., I deleted my own wouldabeen duplicate)

@freeman the aircraft has emergency lights which have their own internal batteries. They are charged by the SHED BUSES in normal operations.

The aircraft have two main AC generators which directly powers the AC BUS 1 and AC BUS 2 (the main buses). It is through these two buses the whole of the aircraft electrical system is powered when the aircraft is in normal operations. So, yes they are both powered up all the time. The main DC power for the aircraft also comes from the AC BUS 1 and AC BUS 2. Because the aircraft does not have individual DC generators to power the DC buses, the AC BUS 1 and AC BUS 2 have a TR (Transformer rectifier) which converts AC to DC. This allows the powering of DC BUS 1 and DC BUS 2.
Interestingly, again in normal operations it is the left generator which takes the most of the electrical loads of the aircraft. Not only does it power the AC BUS 1 and DC BUS 1 but it also powers the AC ESS and DC ESS BUS. These are essential buses which powers the most critical items of the aircraft. The ESS which stands for essential by the way also have SHED buses, respectively the AC ESS SHED and DC ESS SHED BUS.
If the aircraft loses a generator, a BUS TIE operates which automatically connects the two sides of the electrical system. If for example the number one generator fails, the BUS TIE will close the contractors and allow the generator number two to power the left side. If the APU is available it can be started and this will again separate the two sides as the APU generator itself will power the left side. In a situation where you have two generators lost or if you lose the AC BUS 1 and 2, a device called a RAT (Ram air turbine) extends from the left belly of the aircraft. The RAT then powers the hydraulics (Blue hydraulic system) and the hydraulics run an emergency generator. This generator can power the AC ESS and DC ESS BUS. As the emergency generator can only provide AC power, the DC ESS BUS is powered by an ESS TR (Essential transformer rectifier). When powered the RAT the SHED buses are disconnected so that only the most important aircraft systems are powered.

Here you see the GEN 1 failed. The GEN 2 takes over the left side.
In the situation where the RAT fails to work the aircraft can degrade into batteries alone. The batteries are normally disconnected in flight if they are fully charged. When the batteries power the aircraft it again powers the AC and DC ESS BUS. As they are DC, to feed the AC ESS, a static inverter is used. The batteries can power the aircraft for about 22 minutes. But it can be extended to 30 minutes by following a QRH procedure which involves turning the main flight instruments for the flight and relaying on standby ones. According to the procedure the can turn off the only remaining Air data reference (ADR) computer which will then power of all the main cockpit flight instruments. Then you can fly on those small standby instruments until coming in for landing where you can turn ADR back on.


text:
Why would helicopters not have black boxes?
Is there a legitimate argument against having a black box on helicopters? I'm assuming there must be reasons beyond financial ones?

Is financial not legitimate?

They're not always mandatory.

This kind of goes hand in hand with the media publishing articles about the helicopter not having GPWS, and saying it could have prevented everything. It wouldn’t have, mainly because he was flying SVFR and very low to the ground, therefore it would have been turned off. Just in case you were curious about this issue too.

Airline and commuter type aircraft are required to have cockpit voice recorders and flight data recorders. There are no requirements for any other type of aircraft to have them.
Most helicopters are actually small or light aircraft. The helicopter in which Kobe Bryant and others died would be considered a medium sized helicopter, but a small aircraft.
You will find VERY few non-airliner or non-commuter aircraft have any type of “black boxes” as they’re commonly (and erroneously) called. They are not required to, either. Expense, weight, complexity, and maintenance are all reasons. The smaller number of lives at risk might be another. After all, they carry the same number of people as between a sports car and a passenger van. School and passenger buses carry more people.
Saying that, technology has become cheaper and more compact in order to provide de facto recorders. Some modern avionics have that function built in. With the proper app, iPhones and iPads have that function. Some pilots will go the extra step and buy their own sensors to provide more accurate data on Attitude, Heading, Position, Altitude, Ground Speed, Carbon Monoxide presence, and Traffic Data. Add-on apps will even record voice transmissions picked up by the headsets and audio system. This is not mandated by the FAA. It is more for the pilots Situational Awareness and review for training purposes. ForeFlight, CloudAhoy, Stratus, Sentry, and Lightspeed are some common devices and apps used to record data.

"There are no requirements for any other type of aircraft to have them." That is not true according to the answer Koyovis linked above.

You are partially right and I am partially wrong. The link still describes the requirements for airline and commuter type aircraft. If the aircraft is below 12500 pounds, and has less than 10 passenger seat, and not be certified to require more than 1 pilot, it does not require recorders.

I'd argue that calling it a black box is not an error.  That's just the generic term for it at this point.  It's not super accurate, but everyone knows what you mean when you ask about "the black box".

The black box is orange. A green card is pinkish. You park on a driveway. You drive on a parkway. Military intelligence isn’t. Neither is common sense. Laurel is actually pronounced Yanni. English. Go figure.

@DeanF. Actually, I park and drive on a driveway and I drive and park on a parkway, so it's partially accurate

@pushkin - George Carlin would be appalled.

@DeanF. Point of note, my Green Card is green... I assume that is why it is named such.

@DeanF. you can run on a walkway, but don't try to walk on a runway.

@Lady_A - My wife’s green card is pink. She has been here a long time, though. Way before they had expiration dates for permanent resident aliens. She is from Venus.

I've no idea who Kobe Bryant is (presumably a topical reference) but how does mentioning him/her add anything to this answer?  It's not a name mentioned in the question, so it's hard to see any relevance.  It would be simpler and clearer to state that it depends mainly on size and passenger capacity of the aircraft, rather than making readers double-take wondering what context they are missing (particularly in future years when even those who recognise the name now might no longer do so).

It's a bit of an exaggeration to suggest that portable devices can be installed with flight-recorder software - are they really able to record pilot inputs and control surface positions, for example?  Or do you just mean the CVR function in that sentence?

Great info, clearly laid out. A pleasure to read and learn. Cheer!

On the "weight" point, there was briefly a suggestion in the UK to make transponders mandatory, on the grounds that a plane would already have an engine battery, they already had a radio and various other equipment running off that battery, and the cost of a black box was relatively low compared to the cost of a plane.  The sailplane-glider and balloon pilots all pointed out that they didn't have engines nor batteries.  And the hang-glider and paraglider pilots pointed out that the weight and cost of a battery and transponder would be substantially more than the aircraft.  It didn't happen. :)

@TobySpeight even with the passage of time the crash that killed Bryant will remain one of history's highest-profile helicopter crashes with no living witnesses and no FDR. Unless the timing of the question is an honest coincidence, it would be better for the question to mention this motivation, as either way readers will be interpreting that derivative question "why isn't there an easier way to find out what happened in that crash?" to be implied for at least some time, and it makes sense for the answer to address this.

@TobySpeight  - The recent flurry/spate of questions about helicopters and black boxes on this site can be traced back to the Kobe Bryant crash. If Messi, Ronaldo (either Brazilian or Portuguese), Federer, Rafa, Madonna, Beyoncé, Ajay, Shaq, Beckham, Tiger, Oprah or any other mononymously known person were to die under similar circumstances, people would lose their minds wondering the what ifs. People, especially those not in aviation, would flock to sites like this to seek answers. You or I might not know who they are. But, millions of people know, love and adore them to the point of worship.

@TobySpeight - Although the ability to record pilot inputs to flight controls and their responses may not be possible with the current devices, the parameters that I listed are. With new engine monitoring tech, the recording of engine performance is not too far behind. With that, the inferences made using that data would be better than no data at all.

By the way not knowing or being a fan of the people involved in a crash bears little on the notoriety of the incident. Once told of the crash, you may have to Google the celebrity to understand the context. It’s just a few extra keystrokes. For example: J.P. Richardson, Ritchie Valens, Buddy Holly, Hawkshaw Hawkins, Cowboy Copas, Patsy Cline, Randy Rhoads, A aliyah, Otis Redding, John Denver, Stevie Ray Vaughn, Payne Stewart, Brazil's Chapecoense soccer team. Some people’s legacy will live on past the lifetimes of any of us posting on this site.

@Dean, I've heard of Madonna, but most of your list of supposedly well-known names is a mystery.  It's hard to make assumptions about the cultural context of the world's population when you see only a small subset that corresponds to your own particular interests.  (And yes, I have been to Wikipedia and discovered that Bryant was a sportsman in the US; it still seems unreasonable to expect your whole audience to know that.)

@Toby, that is my point, exactly. You are making an assumption about the cultural significance of this crash based on whether YOU know the people involved. You are forgetting that the small subset you speak of is 20% of the world’s population. That is not insignificant for this site considering the fact that particular 20% is part of the 51% of the world’s population that has the internet easily accessible. The above names that I chose are not well known in this subset. But, they are very well known in other, equally large if not larger subsets. That makes them also as significant.

A quick review of this site will show a marked increase in helicopter, SVFR and black box questions right after the crash. The questions, answers and comments all tend to mention this accident in one way or another. Every US news outlet and sporting event has made mention of Kobe everyday since. Even before the crash, I have seen people wearing his sports jersey in countries as far away as China, the Philippines, South Africa, England, Germany, Italy, and Spain. These facts, plus the fact that StackExchange is located in Kobe’s home country, make the Kobe crash one of particular interest here.

To elaborate on Dean's points:

Weight is important in an aircraft. Small items matter more in a smaller aircraft. Large aircraft can more easily afford the several extra kilograms added by the weight of a recording device, its crash/fire protection, mounting, interconnection with the aircraft's power and other wiring to feed the data it is to record.
Cost is important in small aircraft. Not just the recording device itself, but every parameter to be recorded has to come from a sensor or instrument designed to output a signal the recorder can use; it all comes at a price.
Certification. Every piece of equipment installed in an aircraft must meet certification requirements so that it doesn't cause a safety issue and ultimately become the reason an aircraft crashes or otherwise harms its occupants. Certification processes take a lot of time and money. For a flight recorder, its value comes from its ability to work reliably and provide recoverable data after a crash. It all adds up to an expensive undertaking.

Anthony, Much thanks for the thoughtful, insightful response, especially informative is the 2nd para, and the 3rd reminds me of life out west in Canada years ago. A mutual friend owned a small aircraft company and would complain that only when the weight of the paperwork equaled the weight of the aircraft would Transport Canada allow it to fly. All the best and cheer from Paris!

Most of the arguments against flight data recorders are moot - because of technology developed in the past decade.  The same technology in a "smart-watch" that allows it to be a telephone, a camera, a computer, and more....is what now makes it possible to have a FDR and CVR that weighs about 6 oz.......one that also has computing power sufficient to contain the entire digital terrain database.....and an algorithm that tells the pilot when he flies too close to the ground.....even when that pilot has no idea where the ground is.  As for wiring every instrument into a data recorder, the Army in 2008-9 worked with a small avionic company to build a camera that took photos of the cockpit instruments -- it cost only $3900 and weighed less than 1 lb.  It's standard equipment on some small helicopters today....and has been used by NTSB in several crashes to determine causes.  Such devices are FAA/EASA approved.  Most arguments against helicopter FDRs and CVRs are based on unsupported claims of "too heavy, too big, too expensive".  Not today, folks, not today!  Wake up to 21st century technology!

Technology has nothing to do with it. Even if you could build a $5 FDR, it would cost millions to certify it per model of aircraft, which has to be spread across the tiny number of units sold. You’re also assuming the aircraft has the dozens of sensors required to feed your FDR, which most small aircraft don’t, and adding them could easily double or triple the cost of those aircraft for the same reason.

source: Stack Exchange

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

sort: votes


text:
Why does only the right outboard aileron on the A320/340 float up when the aircraft is in the emergency electrical configuration?
When the A320/340's RAT is powering the aircraft's systems, the aircraft goes into its emergency electrical configuration; one of the effects of this is that the right outboard aileron becomes unpowered, and floats up.  Why does only the right outboard aileron go into the upfloat position?

EDIT: This answer is specific to the A340; the A320 is somewhat different.

TL;DR
In the emergency electrical configuration, neither of the two remaining flight-control computers can control the right outboard aileron, and it floats up under aerodynamic forces.
Long version
Some background: all Airbus aircraft from the A320 onwards have five flight-control computers, which translate the pilots' control inputs into control-surface movements.
These are divided into two categories:

Three flight-control primary computers (FCPCs, also known as PRIMs, for "primary"):

FCPC 1 (also called PRIM 1, or P1 for short)
FCPC 2 (aka PRIM 2 or P2)
FCPC 3 (aka PRIM 3 or P3)

Two flight-control secondary computers (FCSCs, also known as SECs, for "secondary"):

FCSC 1 (also called SEC 1, or S1 for short)
FCSC 2 (aka SEC 2 or S2)

Not every flight-control computer can control every control surface; the most critical controls (such as the elevators) are connected to four, or even all five, computers, while less critical surfaces only get two, and the least-critical (the individual spoileron panels) are connected to just one computer apiece (as there are six spoileron panels per wing, with each of the five computers controlling at least one panel on each wing, providing a great deal of redundancy).
On the A340, each of the inboard ailerons is connected to four of the five computers (FCPC 1, FCPC 2, FCSC 1, and FCSC 2); by default, the left inboard aileron receives input from FCPC1, falling back on FCPC 2, FCSC 1, and FCSC 2 (in that order), while the right inboard aileron defaults to FCPC 2, with FCPC 1, FCSC 2, and FCSC 1 to fall back on.
However, each of the A340's outboard ailerons is connected to just two computers.  Both outboard ailerons default to FCPC 3; the left outboard aileron has FCSC 1 as a backup, while the right aileron falls back on FCSC 2.
The A340's RAT can only generate a limited amount of electrical power, especially since a considerable amount of its output has to go into maintaining pressure in at least one of the aircraft's hydraulic systems, in order to allow the aircraft to remain controllable; normally, the hydraulic systems are pressurised by engine-or-APU-driven pumps, but, if the aircraft runs out of fuel (one of the very few circumstances that can simultaneously render all engines and the APU inoperative, and the main reason why the RAT exists), only the RAT is left, and it has to provide both electrical and hydraulic power.  As a result, a lot of electrical load-shedding has to take place to reduce the aircraft's electrical demand to something the RAT can handle; as part of this, three (for the A340) of the five flight-control computers are powered off, leaving only FCPC 1 and FCSC 1.  Additionally, due to the limited hydraulic pressure available from the RAT, the A340's outboard ailerons are deactivated to reduce the demands on the aircraft's RAT-pressurised hydraulics.
The overall effects on the A340's four ailerons are:

Left outboard: Not used; however, as FCSC 1 is still available, the aileron does still receive flight-control commands (although all they do is tell it to stay put), which helps to keep it from drifting away from the neutral position.
Left inboard: Operates as normal.
Right inboard: As FCPC 2 is unpowered, falls back to FCPC 1, and continues to operate.
Right outboard: Not used, and, as both of the two computers able to control it (FCPC 3 and FCSC 2) are offline, receives no flight-control input at all; as a result, its position is now solely dependent on the aerodynamic forces on the aileron, which tend to cause it to float upwards from the neutral point.

As explained in @ymb1's answer to an earlier question of mine:

The manual does not give a direct reason (not unheard of), but in fact there's more than one reason.

► As a quick summary, you lose 2/3 of the spoilers and the outer ailerons, and if more unlucky, you lose 5/6 of the spoilers.
[...]

In emer elec config, the plane loses 3 of the 5 flight control computers; what remains are P1 and S1 (refer to diagram above).
The outer ailerons go into an unpowered state to conserve hydraulic fluid/pressure – the right aileron upfloats* like on the A320 (no P3 and S2).

[...]
The references (click to view):

All images are from the A340 FCOM, and color highlights are mine. Do not use for flight.
A330 vs A340
Thanks to @JZYL, note that there are some differences between the A330 and A340, while the A340 would announce MOST SPOILERS being INOP, the A330 would announce HALF SPOILERS (an extra computer remains powered). The same rationale given should apply though.
* This is also confirmed from [this FCTM][6] (smartcockpit.com) of an airline with both the A330 and A340 in its fleet (see PDF page 207):

(...) The AP will disengage when the failure occurs but AP 1 can be reengaged on the A333 if the EMER GEN is powered by an EDP. As there is no AP available in this configuration in the A340, the Captain must take control and fly the aircraft manually. The A340 aircraft is out of trim in roll due to right outboard aileron upfloat, caused by no power being available to Prim 3 or Sec 2, and neither pitch trim or rudder trim is available. (...)

Note: I haven't found a reason for the different architecture, but ETOPS is a possibility.

(All bolding, italicisation, etc., original to source.  Kudos to @ymb1 for digging up all this information and explaining it to me.)

@ymb1: Edited to state that this answer is A340-specific.  (Also, wait, both posts?  I thought you only answered my question once [and I only referenced one of your posts]...)

all_licenses: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/


text:
Do pilots switch their cell phones into airplane mode?
I think that my question is pretty self-explanatory. I‘m interested in both general-aviation and commercial jet pilots.

I only ever switch to airplane mode for the battery savings.  I use Avare for charts so my phone must be on.

Almost always.
If they don't, you often end up with this annoying sound on the radio:

Ahh, I‘ve encountered such a sound in my FM car radio before. Thanks a lot!

I think it's worth noting that this GSM buzz is characteristic for the  TDMA modulation that is used in GSM (2G) phones. 3G (UMTS) and 4G (LTE) standard phones modulate in CDMA or OFDMA, provided that the base station allows 3G or 4G. These modulations cause much less audible interference. 10 years ago, I heard GSM buzz on daily basis in teleconferences. These days, the sound has become pretty rare. Nevertheless, the absence of audible buzz doesn't mean that there is no interference - possibly impacting your navigation receivers.

Based on my non-scientific observations of GA pilots in the US, I'd say "almost never". It's very common for pilots here to use their cell phones for getting clearances, texting en route, checking weather, activating flight plans and so on. That's not to say it's always legal or advisable, but it's very, very common. Personally, I just forget to put it in airplane mode most of the time.

@Pondlife What clearances would a pilot get in-flight via cell phone? I wouldn't say it's "very common", I've never heard of any pilot, locally at least, that got a clearance or activated a flight plan via phone (in the air). All those services are easily available via FSS.

it depends on the flight.  With a low altitude lower speed ( <200kts) GA flights they can still be useful and can serve as a usefull backup.
Once you travel faster than 200 kts, and higher than about 12,000 you end up switching cell towers too fast and the phone uses a lot of power trying to get as strong enough signal.
If connected to the planes power this will increase the possibility of the phone creating radio interference (analog audio or nav signals)

I fly part time for a small part 135 operator.  Always below 10K' and <200 KIAS.  We have verified that there are no interference issues, and let passengers know that it is OK to keep them on.

The item "Mobile phone ... OFF" is (or at least was) actually a part of the Before Engine Start checklist on several commercial aircraft types. I tried to come up with a reference, but most photos found online only refer to PC simulator software. However, there seems to be one actual photo of the checklists on the cockpit table from a real A320 aircraft found here.
Personally I have seen Airbus (A320/A330/A340) pilots of at least one major European carrier going through that checklist item and accordingly checking and verbally confirming that both their mobile phones were switched off.
(Disclaimer: this experience was 10+ years ago. I don't know whether policies have changed since.)

I am a novice, non-professional pilot. I have never seen anyone (instructors, examiners, other pilots) switch their phone to airplane mode, and in fact it is not uncommon to make cell phone calls from the air. It is also extremely common to use data connected applications (e.g. ForeFlight) from the air.
That being said, it seems like a pretty good idea to keep it in airplane mode when you aren't using it, especially when not navigating visually. As mentioned in some other answers, cellphones definitely can cause radio interference.


text:
Have there been any cases of collision/airprox of small drones with manned aircraft?
Small civilian mini-drones such as the DJI Phantom or professional surveying drones are becoming increasingly widespread, raising concerns about the potential collision/airprox with manned aircraft (especially GA where flight altitude is typically relatively low).

Have there been actual cases of collision and/or dangerous airprox reported so far? What were the consequences?

I reported a drone to ATC flying near the airport at KPAO (Palo Alto) once. Was quite shocking to see it at around 400’ AGL right near the airport.

what is airprox?

@rbp: airprox is short for air proximity, i.e. two aircraft getting closer from each other more than they should.

http://avherald.com/h?search_term=drone&opt=0&dosearch=1&search.x=0&search.y=0

CASA (Australia's aviation authorities) has a report on an airprox between a crop duster and a surveying mini-drone:

ATSB incident report

They call it a "serious incident"? Nothing collided, and it's tiny...

I tend to agree with you, but it should be noted that CASA has been extremely pro-active and efficient at providing a practical framework for commercial operations with small drones. So I wouldn't mind them being a bit over zealous at following up on real world situations...

There was also an incident in Australia (Newcastle, NSW) between a Bell 412 and an as yet unidentified UAV on March 22nd 2014 (investigation pending, details here: http://www.atsb.gov.au/publications/investigation_reports/2014/aair/ao-2014-056.aspx).

Another recent incident - Drone flies 20ft from a jet on approach to Heathrow
http://www.bbc.co.uk/news/uk-england-london-30446136

@DannyBeckett any near mid-air collision is a serious incident. That nobody was hurt is irrelevant

It september 2017, a DJI Phantom collided with an US Black Hawk helicopter causing a real damage to main rotor.
Obviously a military helicopter cannot be destroied by a small uav (why develop expensive Sparrow or Maverick rockets when a simple Phantom could land a military object ;-) ) but... surely it would be a true danger...

There are two instances I remember hearing about.
This one happened to a plane landing at JFK, and the FBI was seeking information about it. They reported seeing a small black "drone aircraft" with four propellers. I don't think they every found anything more.
And just recently, two planes landing at YVR saw an RC helicopter, one plane coming very close to it. The RCMP was investigating, but again it's not certain whether they will come up with anything about it.
There is also an investigation into a video taken from a quadrotor showing a plane landing at YVR.
And if you thought that was close, check out this video from Australia.

This one in Tallahassee with a regional jet got a lot of attention when it happened but there are many more. The FAA keeps a database, and I expect we'll see about an actual collision with a Part 121 aircraft soon enough as the number of airborne UAVs is increasing rapidly.

February 2018 - What is thought to be the first drone collision in the US occurred in February 2018. The National Transportation Safety Board is investigating a helicopter crash landing in South Carolina that may have been caused by a civilian drone, according to a report from Bloomberg.

Obviously, as time goes on, there will be more incidents.
Here, from 2021, a drone and a police helicopter in Los Angeles.

A Los Angeles man pleaded guilty Thursday to a misdemeanor count after his drone crashed into a police helicopter, prompting an emergency landing, federal prosecutors said.

https://www.nbcnews.com/news/us-news/man-pleads-guilty-after-drone-hits-lapd-helicopter-conviction-1st-n1254365

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/3.0/


text:
Where is helicopter rotor attached on Allison Model 250 engine?
Which section of the Allison Model 250 engine is attached to helicopter rotor?

None of it.  The gearbox is.

How is it connected to the gear box?

By a shaft (or mast) to the gearbox output.

Thank You!!! Do you have Allison 250 maintenance manual and can upload by any chance?

Maintenance manuals are usually not public. why are you so interested in this specific model? does it have some peculiarity that other models don't have? how is it special?

I am in Jet Engine Shop at Aviation High School. My team was assigned to work this Allison 250 model. My instructor gave out job sheets pertaining with engine. We have to understand how this engine works in order to pass this class rotation.

If you took the engine out of the helicopter and  ran it, it would work exactly the same.  Why does the main rotor gearbox have  anything to do with the operation of the engine and why is your instructor not teaching you, or giving you reference to materials that you can learn from?

He wants us to research about it first over the weekend. He gives us textbooks but it does not have specific information pertaining to Allison 250.

It's not. The engine is connected to a gearbox that transfers power to the rotor head. I don't know of any helicopter where the engine is directly connected to the rotor head. If it were, the helicopter would not be able to autorotate after an engine failure, unless the failure allowed the engine to continue to rotate.

Not to mention you'd have trouble trying to turn a rotor at 10,000 rpm, never mind whatever higher speed the turbine shaft actually turns at.  IIRC, motor rotors turn at something like 250+ rpm.  Gear reduction is a requirement.

That too, good points! *8)

all_licenses: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/3.0/


text:
Who can sign off the aircraft after completion of 100-Hour Inspection?
Can the mechanic who performed 100-hour inspection sign off the aircraft?

What do you mean by "sign off" the aircraft? And can we assume you're asking about the US (FAA) regulations?

Yes.
In the United States, annual inspections must be signed off by an IA, but 100-hour inspections may be signed off by the A&P that performed the inspection.

In general, that is what differentiates the 100 hour and Annual inspections. Otherwise they are the same.


text:
Why does gas turbine engine have pressure oil supply tube and the scavenge oil tube?
What is the function of pressure oil supply line tube and the scavenge oil tube on turbo shaft engine?

To lubricate shaft bearings? Is this a homework?

Are you asking why the engine is lunricated?

One thing to note here is that with gas turbine engines the purpose of the oil is roughly 80% for cooling of the bearings and %20 for lubrication (also for the bearings). Unlike piston engines where almost 100% of the oil's purpose is for lubrication.

Oil Pressure lines typically sends oil to the Bearings and Gearboxes of the Engine, from the oil pump.
The Scavange lines typically collects the oil from those areas and send it back to the Oil tank, getting cooled and filtered along the way.


text:
What is this high wing twin airplane?

It sits in a very large backyard in Lancaster, California.

for people thinking it's an AeroCommander/Rockwell Commander, it's not. Vertical stab and cockpit windows (as well as the engine nacelles) are quite different.

"very large backyard" indeed!


text:
Why do DC-4 landing performance charts have different values for the intended and alternate destinations?
I am studying the landing performances of the old Douglas DC-4 and there are a lot of different landing performance charts available. The pilots can use different flap settings during landing like 45, 35 and 25 degrees. For these different flap settings there are different charts. But there are also different charts for the Intended and Alternate destinations. Can someone explain to me why there are different charts for these?
How can the landing performance be different just based on intended vs. alternate? For example, in the charts for intended destination it says 60% of runway length and for the alternate destination 70% of runway length.


text:
Does the landing distance required for a wet runway needs to be within a certain range of the landing distance available?
Conform the regulations the landing distance required (LDR) for propeller engine aircraft needs to be within 70% of the landing distance available (LDA). The LDR for a wet runway needs to be multiplied by 1,15 (115% LDR). I was wondering whether this 'wet LDR' also needs to be within the 70% of the LDA to meet the regulations, or does it only need to be within the total LDA?
And does the same count for contaminated runways?

Short Answer = Yes.
Long Answer = landing within 70% of the LDA rule is a HARD limitation. The runway's length does not change with the weather, so the 70% cannot be changed. But, of course, your A/C landing distance does change with weather. Thus, your 115% landing distance required must still be within the 70% LDA.
in practical application, not every landing you do will use 70% of the LDA, or even close to it (It's only a limitation, right?). In many cases, There's still lots of room for your 115% LDR to land safely within the 70% LDA.
Hope this helps!

Hi James!  Welcome to our site.  Do you have any references (to regulations perhaps) which backup what you are saying here?  We like to provide definitive answers with sources when possible.  Also, just in case you missed it, JP93 tagged his question as an "EASA-REGULATIONS" question, so is specifically asking about EASA and not FAA rules (which are possibly the same, but when citing references, it's an important distinction!).


text:
Why does Thai Lion Air use loads of 737 ERs for 1-2hr routes?
Thai Lion Air primarily flies short-haul domestic routes and most of the time I find myself on an ER version of a relatively new 737. Isn't ER for extended range? And thus costs a lot more per plane?
Incidentally their sister company Malindo also has what seems to be an unnecessary amount of ERs (I just flew on one this morning from KUL to BKK - a 110min flight - and one the week before from KUL to HKT, again under 2hrs).

What makes you think they are ERs?

It says so on the tin - the chassis. Also on the emergency procedure leaflet in front of me (737-800ER/900ER). And the wikipedia fleet details.


text:
What does 00 mean on a sectional below the airport runway information?
What does 00-50 mean on the sectional chart under PHNL (see picture)?

It is the elevation (00' MSL) and length (5000') of the seaplane landing runways 04W-22W and 08W-26W. However, I am unable to find a source for that info.

The funny thing is that they obviously wrote it with italicized character O instead of zero. It should have been 00 - 50 but it is OO - 50.

That is the elevation and length of the longest co-located water runway.  Elevation of 00, and runway length 5000 feet.
This information is found on page 16 in the current Aeronautical Chart Users Guide, which states:

Runway length is shown to the nearest 100', using 70 as the rounding
  point; a runway 8070' in length is charted as 81, while a runway 8069' in length is charted as
  80. If a seaplane base is collocated with an airport, there will be additional seaplane base
  water information listed for the elevation, lighting and runway

(emphasis mine)
In this particular chart of Honolulu Int'l, the first line of airport runway info indicates 13 L 123, which is a 13 foot elevation, lighting in operation from sunset to sunrise, and 12,300 foot longest available runway.
The next line down, which you are asking about, is the "additional seaplane base water information", described by the ACUG.


text:
What are the FAI rules for circumnavigating the world?
If I want to solo circumnavigate the world by plane as the youngest pilot, what are the FAI requirements regarding the routing?
Most standard routings include the Hawaii to California leg, which is about 2200NM, a bit far for my plane.
However, I found this guy, who had a max leg distance of 975N. Would that max 975NM variant still be officially acceptable to the FAI?

The FAI has stopped certifying records for youngest pilots as a matter of safety.

"mins" linked to a set of rules at https://www.fai.org/sites/default/files/documents/sc_section_2_2013.pdf , I will try to interpret these in light of your question. I do not take any position on whether those are the official rules and I do not gaurantee my interpretation is correct. I have not read the entire document, just the parts that seemed relavent after searching.
There does not seem to be an official record for youngest flight around thw world. There are records for the fastest round the world (eastbound and westbound) and a circumnavigator diploma (not a record) for flying around the world.
Neither of them seem to have a restriction on the length of invidiual flight legs. Surprisingly other than the polar circumnavigations there doesn't seem to be any requirement to cross the equator.
The author of the route you posted gives a distance of 21738 NM which translates to 40258 km . The speed around the world (eastbound and westbound) records have a minimum distance of 36,770 km, there does not seem to be a maximum number of control points for this record.
The requirements for the circumnavigator diploma are a bit different, there are a maximum of 20 control points which may reduce the measured distance, but the distance requirement is much lower for the circumnavigator diploma.
So this route seems to pass the critera for both the fastest round the world record and the circumnavigator deploma.

I believe the youngest pilot to circumnavigate the world is https://en.wikipedia.org/wiki/Matt_Guthmiller

The article you link claims he lost the record to  Lachlan Smart but the cite for that statement gives me a http 500

Ah yes, I must have missed that. I did find this link to corroborate - http://www.wingsaroundtheworld.com.au/sunshine-coast-teen-lands-to-heros-welcome-with-world-record-in-bag/


text:
What is the difference between VFR Flyways, Corridors and Transition Routes?
What is the difference between:

VFR Flyways
VFR Corridors
VFR Transition Routes

I can find a Flyway chart on the reverse side of the TAC chart and also Transition Routes in the TAC chart. But where can I find a VFR Corridor chart? I Googled it, but there’s nothing.

Flyway? Sure you don't mean airway?

VFR Flyways
These are the most loosely defined, and can be found on a TAC (Terminal Area Chart) as shown below. They suggest general routes and altitudes near busy airspace to keep VFR traffic out of restrictive airspace. This is one answer to the question of how pilots know if they are inside controlled airspace or not.

VFR Corridors
A corridor is a section of airspace that has been cut out of more restrictive airspace, like Class B, to allow VFR traffic to transit without explicit clearance. There will often be suggested altitudes and frequencies to prevent conflicts. Below you can see that there is a hole in the KSAN class B from 3300 to 4700 ft AMSL.

VFR Transition Routes
These are also found on the TAC as shown below and are charted routes for VFR aircraft to fly through more restrictive airspace. They will require contacting ATC, but provide a route for pilots to quickly request and then fly to avoid having to take a longer route around the area.

See also: Special Flight Rules Areas
Sometimes the basic provisions above aren't enough and the FAA defines a Special Flight Rules Area (SFRA). This defines special procedures and requirements for operating in the area. An example is the Los Angeles area where pilots are allowed to fly through the Class B without contacting ATC as long as they follow certain requirements.

You re a genius!! Thx A LOT!


text:
Why is there no airport beacon light symbol on the sectional for KSAC, although it does have one?
The star symbol on the top of the airport means airport beacon light but
Sacramento Executive (KSAC) has no star symbol but they do have a beacon light and controlled airport as well.
Is that misprinted or any reason for that?

I believe it's because the beacon doesn't operate continuously.
The FAA Aeronautical Chart Users' Guide says:

The symbol [...] indicates the existence of a rotating or flashing
airport beacon operating from dusk to dawn.

However, KSAC's beacon doesn't operate from dusk to dawn; pilots have to activate it using CTAF, in the same way they can activate pilot controlled lighting. The Chart Supplement for KSAC says:

When twr clsd ACTIVATE arpt bcn—CTAF

I assume that because the beacon isn't operating continuously, showing it on the chart would be misleading to pilots who aren't aware of the Chart Supplement information. If you look at the airport diagram for KSAC, you can see it uses a different symbol from the standard one for the beacon.


text:
My medical cert is expired and can I fly as a sport pilot?
I'm CFI and one of my student haven't flown after he got his private pilot license in 1990's and he wanted to fly again. The thing is his medical is expired already and he doesn't fit medical standards anymore so we're aiming for sport pilot privilege(He isn't qualify for BasicMed also he got his medical before 2006). Can he fly as a sport pilot with his private pilot license with driver's license?

So it was just expired, not cancelled?

If his last medical expired valid before July 2006, it’s now like he has never had one at all. (A denial or revocation would be different.)
However, if he does not believe he could pass a medical exam today, I would point out that FARs 61.53(b), 61.23(c)(2)(iv) and 61.303(b)(4) still prohibit sport pilots from flying if they are aware of any condition that would make them unfit to fly.
This rule is widely ignored in practice, but it is your responsibility as a CFI to point it out—and it would be wise to have proof that you did so in the event he ignores you and then has a health-related accident.

I might add, that if you as a CFI, or actually any person for that matter, is aware that someone not fit to fly is about to do so, you are obligated (by not only aviation law), to prevent that from happening...

I think a lot of CFIs are too worried about liability from their student crashing. If the guy has a heart attack and crashes, the FAA isn't going to go after the CFI unless there's paperwork missing or something. It's on the PIC (the pilot) to make sure they are fit to fly, not the CFI.

@PilotDan When the pilot tells a CFI they have health problems that may make them unfit to fly, things change—at least morally. I’ll leave liability to someone more qualified, but since the CYA is just mentioning it in your logbook entry, why not?


text:
Is the purpose of variable pitch propellers to maintain an optimal angle of attack?
I recently had a discussion with an aviation expert, who works as a Flight Instructor, about constant speed propellers - variable pitch propellers - on light piston aircraft.
I have always known that these kind of propellers are capable of changing their pitch angle in flight in order to keep propeller blades at their optimum angle of attack across a wide speed range, while maintaining constant RPM. Therefore, they are very efficient over a wider airspeed range compared to fixed pitch propellers. A change in TAS in flight, for example, would lead to a change in pitch, in order to restore the optimum angle of attack of the propeller blades.
To my surprise, the instructor told me that what I knew about variable pitch propellers was not true: he explained to me that a change in TAS during the flight would lead to a change in the angle of attack of the blades, but that doesn’t mean that the resulting pitch change would lead to the optimum angle of attack.
His answer really surprised me, so I am now wondering what is the purpose of variable pitch propellers then. I understand that there may be a point where the PCU and CSU won’t be able to adjust the pitch to the most optimum angle of attack, but I thought that during normal operating speeds the purpose of this kind of propellers was to provide the blades with the most efficient angle of attack. Am I wrong?

Optimal angle for what property?

What you know about variable pitch propellers is generally correct. If you make a slight change, your flight instructor would not have had any reason to object: They keep propeller blades near their optimum angle of attack across a wide speed range.
As the distance from the hub increases, the blade section gains circumferential speed while being in the same forward speed as all other sections. Therefore, the twist of the propeller blade should change linearly from the hub to the tip. If you twist the full blade at its root, you add a constant change to each cross section, so at high speed the root of the blade sees too high an angle of attack and the tip has too little angle of attack. Normally, the section at approximately 75% of propeller span is kept at its ideal angle for the best overall compromise. That is good enough for practical use.
Ideally, the propeller would spin faster with increasing flight speed, but that would require a gearbox and switching gears with the limited speed ranges of combustion engines, would deliver little thrust at the beginning of the take-off run and at high speed you would run into compressibility problems at the tips much sooner - practical high speed propellers spin more slowly than typical low-speed propellers.
If you look at the efficiency chart of a three-bladed variable pitch propeller below, you will see that efficiency peaks for one speed (given as an advance ratio in the plot below) and one pitch angle. This is when the full blade is flown at the optimum angle of attack for each section. This optimum would shift to higher speeds for less twist and lower speeds for more twist. Operating the propeller away from its design point incurs small losses since not all of the blade is exactly at its optimum angle of attack, but if you compare the overall efficiency with that of a single pitch setting, the advantage of variable pitch becomes obvious.

Efficiency chart of a variable pitch propeller. Source: McCormick B.W. Aerodynamics, Aeronautics &Flight Mechanics. John Wiley & Sons, Inc., 1979.

Hi Peter, what does the efficiency of a variable pitch propeller exactly mean? Is this a ratio between blade drag during rotation and thrust? Am I right to assume that during take-off, for an engine it would be "easier" to rotate a propeller who's blades are at 15 degrees pitch rather than 45 degrees?
Also, if a stationary turboprop aircraft will use 45 degrees pitch during take-off, will this result in less thrust compared to 15 degrees pitch? Thanks.

@ElectricPilot: Propeller efficiency is the ratio of thrust times speed and net engine power. It only shows how much of the power produced by the engine (minus what is diverted for driving accessories, therefore net power) is converted to useable thrust. Pitch does not figure here directly but is important to maximize that efficiency. Yes, it is easier to drive the propeller at fine pitch but not necessarily more efficient. How much thrust is produced depends on the local angle of attack at the blade, a single pitch number does not reveal this.

The purpose of a variable pitch prop is to allow is to allow the pilot to select where on the engine's power curve (s)he wishes to operate the engine. When full power is needed, as for takeoff and initial climb, the throttle is fully opened and the pitch set as shallow as required so as to allow the engine to spool up to the peak of its rated power curve. For economy cruise, the prop pitch is deepened to load the engine down to a lower rotating speed at which it produces less power and consumes less fuel.
In this regard, you can consider the pitch control on the prop as the analogue of the transmission in your car: First gear = fine pitch, top gear/overdrive = coarse pitch.
Note here than this means a constant speed prop and engine combo to be the analogue of the cruise control system in your car.

There are two kind of propeller:

Fix pitch propeller, which the pitch or we more familiar to say as the angle of attack (AoA) always same all the time, engine RPM is adjusted to meet requirement.
Constant speed propeller, which the engine RPM is variable due to the change in the pitch.

The first propeller is the old one, and cheaper. No chance to change the pitch. The pitch is normally low, around 5 degree (depend on the producer's design). The latter one is more expensive and more suitable to be used in current flight. A propeller with low pitch is suitable for take off, while high pitch is more suitable during cruise. "High" here is depend on the producer, but will be around 15 degree, the maximum limit before it get stall, which mean the power from the engine is no more effective to move the airplane forward.
Low pitch with the fix pitch propeller we can think like a car with low gear which is used to move a car from stop and then climbing a hiking road. And after some distance, meet a flat and smooth toll road. During climb, gear 1 (low pitch) is more suitable, but not while cruising in the flat and smooth toll road. During cruising in that toll road is more suitable using gear 5 (high pitch). The same thing is also apply to airplane. During take off, airplane requires low pitch but high RPM. That to allow the propeller to "bite" the air small by small, and slowly pull the airplane move forward, then take off, until it meet the cruise level. After cruise level (which the airplane will force to be high speed), the propeller is adjusted with the suitable pitch to meet the suitable RPM, which is lower RPM but higher TAS or at least same TAS. Lower RPM mean lower piston stroke per minute. Lower piston's stroke per minute mean lower gas consumption. So, the instructor word with "optimum" is mean "best gas consumption due to the lower RPM". Lower RPM will reduce the engine temperature, and finally will lengthen the engine life cycle.


text:
Does the FAA allow a jet bridge to approach an aircraft that has engine #2 running?
Does the FAA allow a jet bridge to approach an aircraft that has engine #2 running?

On a two engine airplane, Engine #2 will be on the opposite side from the jetway, and keeping the engine running while the bridge is connected on the other side is not an issue.
(see related question: How are engines numbered?)
On a 4 engine airplane, Engine #2 will be directly behind the jet bridge, and should be shut down before the bridge is extended.  This is for the safety of the engine, to avoid ingesting any debris from the jet bridge, or debris dropped by people, rather than for the safety of the people (who are unlikely to be sucked in by an engine at low power).

If the engine is running at a low / idle power, it would not suck in a person.  But if a passenger / crew dropped anything small: pocket change, pens, keys, etc, those could be sucked in and damage the engine. (edited for clarity)

Many thanks!!!!!


text:
Why would you NOT lean on takeoff with a Lycoming engine?
There is an excellent question/answer on leaning here. However what I have not yet understood is why one would NOT lean for takeoff below 3000 feet? Why does the Lycoming Service Directive 1497A/B still say to use Full Rich on takeoff?
Is it not right that a leaned engine is producing its highest power output and would you not want the highest power output on takeoff?

The air is dense below 3000. You won't gain much by leaning that low. It's much better to trade a few HP for better cooling. Note that the SB specifies DENSITY altitude, not just indicated. A hot day in Phoenix will push you well above 3000' DA despite being only 1500' MSL. In this case, leaning before takeoff is appropriate.

You are correct - you do want highest power.  But you also want an engine that doesn't overheat and destroy itself.
Your initial climb-out is at an airspeed considerably less than cruising speed so you have less air flowing through the cylinder cooling fins.  To compensate for this, flying full rich keep the combustion gasses cooler during the climb-out.
When you reach cruising altitude and level off, you may lean it out in accordance with the engine manufacturer's recommendations.
This "full rich on takeoff" procedure is not limited to Lycoming engines, either.  TCM Continental and even the older Pratt and Whitney radials also go full rich on takeoff. It is close to a universal procedure for piston powered aircraft engines.

Another great plus about this is that it means that you can lean for more power should you ever discover that you don't have quite enough power to complete the takeoff safely. If you screw up calculating the weight, density, or distance, if you realize it soon enough, you can lean the engine and live to talk about it.

Full rich for max cooling when making high power. At higher altitude airports, air is thinner so you lean for the max power you can get at that altitude to be able to make it out.


text:
What is the purpose of including sea level pressure and temperature in a METAR?
In a METAR such as this one:

KGOK 161553Z AUTO 18011KT 4SM BR OVC007 07/05 A3011 RMK AO2 SLP201
  T00670050

Translated to:

Jan 16, 1553Z, Automated. Mist, Wind from 180° at 11 knots, 4 statute
  miles visibility, Ceiling is Overcast at 700 feet, Temperature 7°C,
  Dewpoint 5°C, Altimeter is 30.11. Remarks: automated station with
  precipitation discriminator sea level pressure 1020.1 hectopascals
  hourly temp 6.7°C dewpoint 5.0°C

Why would I want/need to know, or what would I do with, this information in the remarks section:

sea level pressure 1020.1 hectopascals hourly temp 6.7°C dewpoint
  5.0°C

Are you asking about why the values are present at all (07/05 A3011 is the first time, and absolutely essential information in the report), or why are they given twice (SLP201 T00670050 is the second time, as a remark, with a bit of extra precision)?

You forgot “baby rain” (aka mist) :)

It is additional information for reference use. A pilot in the US will not typically use the additional information unless they have an altimeter calibrated in hPa, but a meteorologist might be accustomed to working in hectopascals (or millibars). The additional temperature/dewpoint data is also more precise -- to the tenth of a degree C.

The hPa is also useful for international pilots arriving from locations where they typically use hPa instead of inches of Hg. All airliners can switch between the two units, but pilots like what they use most often.

Why not use Q1020 in the main section, as done in other countries, rather than putting it (in a different format!) in the remarks section?

@StephenS, the remarks section has extra precision. I suspect it is there for the benefit of meteorologists, because pilots don't need it.

@StephenS, "Why not use Q1020 in the main section, as done in other countries..."  Because we are Americentric!  ;)

@Gerry Not all airliners in all places... a common exception was the mechanical Airbus standby altimeters which only had one unit, so they often had a decal somewhere with the conversion. (Even more annoying if the plane originally came from the wrong place and the airline was too cheap to swap out the unit)

The sea level pressure allows pilots to calibrate their altimeters to make sure they are accurate. KGOK is 1069 feet elevation, if a pilot were to set their altimeter to 1020hpa (or 30.11 inches of mercury as used in the US, that's the A3011 in the METAR) then their altimeter would read 1069ft at ground level.

Ok so it is helpful to know that those two things are related (A3011 and the RMKs about sea level pressure) and I know what I would do with the A3011 to set my altimeter; what causes me to ask this question was: why the extra information if it is already communicated with A3011?  I am not sure that it is at all useful beyond what A3011 tells me.

Whatever site is translating that METAR for you is converting the measurements @user2325243.

+1 answer  Above Sea Level  and Above Ground Level may apply differently.  Local flight would set altimeter for AGL.  Cross country would set ASL (or AGL of destination).  Changing weather will also factor in.  I believe (correct me if I'm wrong) flight levels are in ASL.

The two pressure values given in the METAR string are clearly not simply the same value just being repeated in different units.  See for example this METAR, given in coded and decoded forms (source: https://aviationweather.gov/adds/metars/index?submit=1&station_ids=KIAB&chk_metars=on&hoursStr=2&std_trans=translated&chk_tafs=on ).  The second value is the more accurate one because it is corrected for non-standard temperature and this is the value that would be used to obtain "calibrated altitude", but the first value is the one that pilots actually use to set their altimeter to get "indicated altitude".

METAR text:   KIAB 271456Z AUTO 25007KT 10SM CLR 22/12 A3004 RMK AO2
SLP168 T02190119 51005 $

Conditions at:    KIAB (MCCONNELL AFB , KS, US) observed 1456 UTC 27 May 2022

Temperature:   21.9°C (71°F)

Dewpoint: 11.9°C (53°F) [RH = 53%]

Pressure (altimeter):  30.04 inches
Hg (1017.4 mb) [Sea-level pressure: 1016.8 mb]

Winds: from the WSW
(250 degrees) at 8 MPH (7 knots; 3.6 m/s)

Visibility:    10 or more miles
(16+ km)

Ceiling:   at least 12,000 feet AGL

Clouds:    sky clear below
12,000 feet AGL

Weather:    SOME DATA ABOVE MAY BE INACCURATE!!! "$" is
an indication the sensor requires maintenance

Also addressed here -- Why are the airport pressure values for "altitude" (inHg) and "sea level" (mb) slightly different on the NOAA web sites?


text:
How can I acquire an N number that's showing as deregistered?
I'd like to use an N number that is listed as available. But when I request it, it shows as being deregistered. How can I get this number for my aircraft?

If the number is deregistered, you cannot re-register it unless you have the previous registered owner of that number submit a request to relinquish the number to you.
So you must get in touch with the old owner of that N number, and if he is willing to write a letter relinquishing it, all you should have to do is send his letter in with your request and a check.
If you have any other doubt, this page has information about your issue:
About Aircraft Registration Renewal
If you need any other information, do not hesitate to comment and I will try to give you a more detailed answer for your problem


text:
Where is Transport Category aircraft defined in CFR 14?
Commuter Category is defined rigorously,
https://www.law.cornell.edu/cfr/text/14/23.3
But I was unable to find an equivalent definition for Transport Category in the regulations (not Wikipedia or the FAA website, haha). Nor was I able to find anything like "if requirements not met for Commuter, then the vehicle is in Transport Category."
Could somebody point me in the right direction?
Thank you.

Maybe you want Part 25, Airworthyness Standards for Transport Category Airplanes instead of Part 23?

According to the FAA:

Transport airplanes are airplanes for which a type certificate is
  applied for under part 21 in the transport category and that meet the
  transport category airworthiness requirements. Multi-engine airplanes
  with more than 19 seats or a maximum takeoff weight greater than
  19,000 lbs must be certificated in the transport category.

In other words, there are two possible reasons why an aircraft is transport category: the manufacturer applied for a transport category type certificate, or the aircraft has more than 19 seats or MTOW greater than 19,000lbs.
The first reason refers to 14 CFR 21.21:

An applicant is entitled to a type certificate for an aircraft in the
  normal, utility, acrobatic, commuter, or transport category, or for a
  manned free balloon, special class of aircraft, or an aircraft engine
  or propeller, if—
[...]
(b) The applicant submits the type design, test reports, and
  computations necessary to show that the product to be certificated
  meets the applicable airworthiness, aircraft noise, fuel venting, and
  exhaust emission requirements of this subchapter

The "applicable airworthiness, aircraft noise, fuel venting, and exhaust emission requirements of this subchapter" for transport category aircraft are in part 25, AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES. If your aircraft meets those requirements and you get a type certificate from the FAA, then you have a transport category aircraft.
The second reason refers to 14 CFR 23.2005(a):

Certification in the normal category applies to airplanes with a
  passenger-seating configuration of 19 or less and a maximum
  certificated takeoff weight of 19,000 pounds or less.

That means, if your aircraft exceeds 19,000lbs then you can't certify it in the normal category (part 23), which leaves only transport (part 25).
By the way, the 23.3 regulation you quoted doesn't exist any more because part 23 has been completely rewritten.

Great answer, I had no idea about 14 CFR 23.2005(a). Thanks!

I'm not sure there is an explicit definition, but the transport category is basically supposed to be "anything too big to qualify for Part 23." There are no general restrictions on what aircraft can be transport category, except that it basically has to have at least two engines. But even that could be open to interpretation. The requirements are generally more strict, so for the most part an aircraft will use Part 23 if it can.


text:
What authorization do I need to fly a rebuilt aircraft that doesn't have an airworthiness certificate yet?
Let's say I rebuild an aircraft in the USA and it does not have a current airworthiness certificate. The DAR requests a check flight during the process of issuing the new airworthiness certificate.
My question is: do I need a check flight authorization or permit from the FSDO to be able to fly without an airworthiness certificate?

Welcome to Aviation.se! I assume since you mention FISDO's that you are asking about American regulations. You should add that to your question as answer may vary by jurisdiction.


text:
How can I calculate a gradient using a Jeppesen Student Flight Computer?
On a Jeppesen Student Flight Computer (CSG), how does one calculate the gradient in percentage if the ground distance and height above ground level are given?
I can't find anything in the accompanying manual. Apparently this is possible on the E6B and CRP-5.

Can you provide a sample problem?

I figured it out. It works the same way as with the CRP-5. If for example the ground distance and height above ground level is given, then one aligns the ground distance on the inner scale (the B scale) with the height above ground level on the outer scale (A scale). Then look up the number 10 or 10 mark on the inner scale (the CRP-5 has an additional red arrow for this mark), and read the gradient in percentage on the outer scale.

Instead of commenting, you should post this as an answer on your own question to help anyone who finds it in the future. Comments are liable to be deleted.

It works the same way as with the CRP-5. If for example the ground distance and height above ground level is given, then one aligns the ground distance on the inner scale (the B scale) with the height above ground level on the outer scale (A scale). Then look up the number 10 or 10 mark on the inner scale (the CRP-5 has an additional red arrow for this mark), and read the gradient in percentage on the outer scale.


text:
How far can one be from an helipad when marshalling an helicopter?
I considered 25 meters (as per UN SOP's) but after working years with MI-8's the downwash can flatten a big man. I'm interested in procedures from the FAA etc. ...

I'm not sure the FAA has regulations regarding this. There is a chapter in the FAA Helicopter Flying Handbook about ground safety, but no specific distances are called out. Only that it would be difficult to develop one policy for all helicopters.

This question is incomplete: are you only concerned with MI-8's?  If so, make sure you question says exactly that.  Size matters.  If you want a general rule, the question is too broad (per @RonBeyer comment)

Can't find any rules about marshaling helicopters in Canada other than the signals themselves, If its an air operator the "AOC" once approved is considered law, so any any restrictions in that document would be considered regulation in Canada. As for an FOB, nothing found for Canada.


text:
Pitot Measurement
Very many years ago i used to suddenly align then flare to stall at almost exactly where I wanted to touchdown. Later, I tried to analyze why I had bounces.
Does a pitot tube measure the axial component of a crabbing aircraft's airspeed or the actual airspeed?

It does, but very indirectly and not in a way that is of any use. Since it's measuring dynamic ram pressure entering a little hole, any time the hole is not perpendicular to the flow, the presented opening area gets smaller and the dynamic pressure drops.
To visualize, take it to an extreme, say an angle of 45 degrees to the airstream, and the opening, looking at it from straight ahead, is an oval of much smaller area, so the dynamic pressure will be lower.
It's why the indicator reads low near stall speed, and one of the reasons you have to calibrate the speed indicator (that and to compensate for local flow velocity variations at the probe) on larger aircraft.
So when you are landing or just flying slowly with a very nose high attitude and high angle of attack, the airspeed will read several knots lower than the actual "calibrated" airspeed. Same if you are landing with a lot of side slip.
So a STOL technique in a strong crosswind could give a larger error than no crosswind and you may find your sink rate is higher, with a given speed indication, in a strong side slip than with no side slip.
Beyond keeping that in mind, I can't think of a way to actually measure that accurately enough to use, without vanes to measure the actual slip angle like test aircraft use.


text:
Do carriers such as Janet Airlines carry ADS-B transponders?
I was doing some casual browsing and came across some videos related to Janet Airlines. This is something I remember hearing of many years ago but this happened to jog my memory.
What jurisdiction would such an airline fall under? From the Wikipedia article:

Due to the secretive nature of the airline, little is known about its organization. It is operated for the USAF by infrastructure and defense contractor AECOM through AECOM's acquisition in 2014 of URS Corporation, which acquired EG&G Technical Services in 2002, as derived from URS's history of providing this service to the Air Force and job openings published by URS.

If it's strictly military (all staff appear to require clearances, after all), would such planes be fitted with ADS-B transponders by regulation? If so, couldn't they just be looked up on websites like Flightradar24?
Also, if an emergency occurred on board, what special treatment (if any) would they be provided if they landed at a civilian airport?

Just a side note: Civilians can get security clearances, but, my understanding is that Janet Airlines provides mainly military/CIA/NSA/OTLA operations.

You can just look them up. Here's a screenshot from Flightradar24 taken at about 1410 UTC on 22 May 2017.
I imagine in an emergency they'd be given priority just like any other aircraft in distress. The crew might have specific orders covering that situation that requires them to head for a military base. Their operation is so secret, though, that I doubt we'd find out unless a emergency occurs.

The aircraft are operated as civil aircraft.  They are not military aircraft.
Sites such as FlightRadar24 have options where an aircraft owner can have their aircraft's flight information redacted.
Their passengers are not limited to military personnel, and they carry defense contractor employees.

Aggregator sites not listing the data does not mean that the flight location is not publically available to anyone with an ADS-B receiver in range of the aircraft.

That is true, and there are many people who monitor those flights.  Kind of a cult following.


text:
What's the maximum bank angle of a glider?
I know that stall speed and wing load increase with the angle of the turn and I have experienced 65 degrees turns in a glider (demonstrated by an instructor).
Let's say a collision is imminent (or we are in some other emergency situation) what would be the theoretical maximum bank angle? I'll check on the placard the next time I'm in the airfield, but I don't think it's in there.

I feel like this question is asked in a very generic way.  Different aircraft have different tolerances.  I believe most fixed-wing aircraft like gliders can continue to bank all the way to 90 degrees so long as the ailerons have enough airflow to provide the torque; although, this would be very dangerous in many aircraft.

Some gliders are capable of aerobatics, so it more depends on limitations of the airframe, and altitude and lift characteristics.

@RyanMortensen All aircraft can handle even inverted flight without  issues if the forces are managed appropriately. See for example the classic videos of Bob Hoover barrel-rolling twins with an engine out.

@RyanMortensen … or Alvin Tex Johnston barrel-rolling a 707. Yes, it is dangerous, but the danger comes from spatial disorientation; the pilot should be trained in aerobatics to do this.

Not sure why it is down voted, and seems like a good question to me. Maximum bank angle would be an aircraft limitation. You would have to look at the aircraft operating specifications. I guess, in one sense, if the collision is  imminent, and let's say, the aircraft is limited to 30 degree bank angle because of power plant restrictions, I would do what I had to do and deal with the power plant failing after the evasive maneuver. If your gonna die, might as well die taking a risk being creative and making things happen.

@falstro I didn't mean to imply they couldn't go inverted.  I suppose, depending on how you look at it, then 180 degrees is the maximum bank angle ;)  I wouldn't say that because Bob Hoover and Alvin Johnson could do it makes it not dangerous.  Your response is akin to saying, "well, Robbie Knievel did it... It's not dangerous if you manage the forces on the motorcycle properly."  If I had stated that jumping the Grand Canyon on a motorcycle is dangerous.  Different aircraft have different tolerances to the forces acting on them. Therefore, risk is variable; not to mention the human factor.

Not duplicates, but closely related and discuss the theory: What is the optimal bank angle to accomplish a given turn in a glide? and What is the maximum safe bank angle of a 747?.

The bank angle ($\phi$) in a stationary turn is limited by the maximal load factor of the aircraft (or the pilot- whichever is less):
$$\phi_{max}=\arccos(\frac{1}{n_{max}})$$
Utility category gliders ($n_{max}=5.3$) have a maximum bank angle of 79°. Aerobatic gliders with $n_{max}$ between 7 and 10 can fly only slightly steeper turns (82°-84°).
If you're flying with an airspeed slower than design manoeuvring speed $V_A$ the limiting factor is the maximum lift coefficient. In that case, the formula gets
$$\phi_{max}=\arccos(\left(\frac{V_S}{V}\right) ^2)$$
$V_S$ is the stalling speed in the current configuration, $V$ the airspeed of the glider.

(own work)
Then, how do you get the tightest turn radius? With high speed and high bank angle or with low speed and low bank angle? Without the structural limitation the radius could become 0. With it, however, your best option to get a minimal turn radius is to fly with maneuvring speed and maximum load factor.
You can use the following diagram to calculate the minimum turn radius at any speed (just multiply the ordinate with the squared stall speed of your aircraft).

As stated in many comments, during aerobatics/dynamic manuevers you can get any bank angle for a certain (sometimes really short) period of time:

0°/180° bank angle Source

90° bank angle Source

I have never before encountered the phrase "stationary turn".  Did you perhaps mean "steady-state turn"?

@quietflyer If you search for the phrase online you'll get multiple results, both on this site and other places (e.g. in official accident reports from the AAIB https://aviation-safety.net/wikibase/46949, or in Torenbeek's aircraft design books). If it makes the answer clearer, feel free to change it

Gliders do not have a technical limitation for the bank angle.
Flying with high bank angle (not turning / "knife flight") does not add any force. Therefor the main problem is to maintain enough speed to  fly stable.
Depending on the aerodynamic design of the glider it might not be  stable to fly at bank angles around 90 degree  and  fall into (steep) spin (trundle) as the speed reduces too quickly. Any glider (as any other plane) must be designed to sustain the forces appearing on a stable steep spin. Given that there is enough height recovering from (steep) spin is quite easy. Some gliders are even designed to recover themselves from the spin (e.g.: ASK-21).
So after all  bank angles around 90 degree are quite safe and for some planes a stable flight is possible (for a couple of seconds).

On the other hand: The scenario you came up with, that you have to avoid a crash into another, plane I'd do a "hard turn" (risking to over-g the plane) rather than a "roll".

Airplanes move in 3D, so banking to avoid a collision should be combined with a climb or a dive, depending on the relative altitude of the opposing aircraft. If you want to maximize turn rate, you would best use an instationary manoeuver anyway (instationary means that lift has not to equal weight during the maneuver).
First to the bank angle limit in stationary flight: This is given by the maximum load factor $n_{z_{max}}$ of your glider which is 6.5g in case of the ASK-21. The equation for the bank angle $\phi$ is
$$\phi = arccos\left(\frac{1}{n_z}\right)$$
When we now look at the resulting turn radius $R$:
$$R = \frac{\frac{n_z}{\sqrt{n^2_z - 1}}}{c_L\cdot\frac{\rho}{2}\cdot\frac{S_{ref}}{m}}$$
we see that more bank will not necessarily make the turn much tighter: You run into a limit in stationary turns where the speed increase needed to create the additional lift for turning tighter requires a bigger turn, and both effects cancel each other. A graphical explanation is given below where the little gliders show which bank angle is needed for the turn radius at which the glider sits. The red dashed line is the load factor at that radius.

Load factor over turn radius, assuming a lift coefficient $c_L$ of 1.4 and a wing loading $\frac{S_{ref}}{m}$ of 35 kg/m² (own work).
In order to avoid other traffic, it might be more advisable to sharply pull up, slowing down the aircraft in the process, and then turning vertically from that climb position when the glider is close to zero g. If you like, you may now invert the plane because there is no limit on the roll angle once you fly such dynamic maneuvers.

I have never before encountered this "stationary" / "instationary" terminology.  Apparently "stationary" = "steady-state"?  To me, "stationary" means motionless.

@quietflyer It distinguishes between maneuvers that can continue for a long time and those that are only momentary. The distinction makes most sense for motorized flight (stationary turn = no loss of altitude). Stationary equals timeless. All important parameters are then motionless, if you will.


text:
What turn to intercept a radial and how to tune in B737ng sim?
Forgive my very amateur questions, I have been out of flying for years now and I am getting fit to fly again after slight setback.
I have an opportunity of doing some refresher flying in 737NG simulator soon. I was given a mock clearance for practice and would like your input. Take off is from runway 30, runway heading till 2000ft and then track and intercept radial 020. The VOR station is right behind the runway at the airport.

Does this clearance allow me to fly a reciprocal of 020 inbound to the station? Or will I just have to fly away from the station on 020 radial?
Will a left turn be more appropriate than a right turn to intercept radial 020?
In a Cessna 172, I would twist the OBS to get a from flag and then select 020, how do I ago about this in a 737 sim? Is it the same thing?
Do I select the radial before or after take off?
Finally, the b737 uses ADI with a movable pointer or "sky up"which is different from what single pistons and light twins use. I will appreciate any tips to help me nail the movable pointer ADI/attitude indicator on the sim.

I will really appreciate any tips to help me make the most of the sim session and sorry for the terribly novice questions.

No need to apologize for beginner questions, we’re used to them.  Welcome to aviation.SE and keep up the great questions.

Does this clearance allow me to fly a reciprocal of 020 inbound to the station? Or will I just have to fly away from the station on 020 radial?

A radial is always pointing away (radiating) from the VOR. The clearance therefore instructs you to fly away from the VOR on the 020 radial.

Will a left turn be more appropriate than a right turn to intercept radial 020?

I think the image should answer that: right turn is better.

In a Cessna 172, I would twist the OBS to get a from flag and then select 020, how do I ago about this in a 737 sim? Is it the same thing?

You can tune the VOR frequency on the ground using the NAV tuning panel on the center pedestal (left image) and then dial in the course of 020 on the Mode Control Panel (MCP) on the glareshield (right image):

(737 NG FCOM)

Do I select the radial before or after take off?

You can do it before takeoff because you will depart using runway heading (in HDG SEL mode) initially.

Finally, the b737 uses ADI with a movable pointer or "sky up"which is different from what single pistons and light twins use. I will appreciate any tips to help me nail the movable pointer ADI/attitude indicator on the sim.

You depart in HDG SEL (8 in image below) with a heading of 300 (or runway heading) until 2000ft and then turn right onto a 065 heading (still in HDG SEL). This will set you up for a 45° intercept of the radial. Note: With strong winds, you need to correct this heading to get a 065 track.
To arm the intercept, you select the VOR LOC mode on the MCP (5 in the following image):

(737 NG FCOM)
This will arm the VOR intercept (should show VOR LOC as an armed mode on the FMA (Flight Mode Annunciator), which is located at the top of the Primary Flight Display). Now all you have to do is follow the flight director (or turn on the autopilot and watch it do all the work).
If you don't want to use the flight director, you can switch the Navigation Display (ND) to VOR mode on the EFIS (Electronic Flight Instrument System) on the glareshield (2 in the following image, when turning 1 to VOR you also get an ADF like pointer towards the VOR):

(737 NG FCOM)
The ND will then look something like this:

(737 NG FCOM)
Here, you find familiar things like lateral deviation (10), TO/FROM indicator (12, also shown as arrow inside) and the selected course (3). It is using heading up or track up, but it works exactly like in a C172. The easiest way to fly the intercept is however to use the flight directors.


text:
How is an air accident's probable cause determined?
I constantly hear that air accidents are caused by a range of shortcomings. However, most accident reports declare a main "probable cause". You can see below a bar-chart with the causes of fatal accidents by decade (data source):

Does anyone know which criteria are used to determine the main accident cause?

The  page you linked actually give the criteria for each of those buckets. Is anything specific unclear?

@Jamiec Indeed, the page breaks down the categories into specific causes, but it does not provide information about how is this cause chosen. For instance, let's say pretend that an air accident involved a design flaw and the crew executed an improper procedure. Eventually, the accident cause was reported as "Mechanical". My question here is: Why "Mechanical" and not "Pilot Error"?

The falacy here is that there is one cause of an accident. They are always a "chain-of-events" which can be broken at any time, and no accident occurs. I think what were talking about here is the major contributing factor. I will try to find a decent answer, unless someone else does here.

Please note that the categorization you talk about seems to be specific to that specific website - not something that is widely used in aviation in general. So to get the best answer you should probably contact the owner of that website.

@J.Hougaard Do you know the standard terminology for air accident causes? Maybe is it different among each Civil Aviation Authority?

It is really hard to answer. How would you categorize a mechanical failure (e.g. engine related) not well handled (pilot related) because of workload increased by bad weather ? One can argue weather is the "initiating cause", and even more if such weather increase the probability of the observed mechanical failure.

@Manu - I think you could argue that's a design or training issue. A mechanical issue during bad weather is a predictable situation, and the design of the aircraft should not require super-human piloting ability. Unless the mechanical failure (or the weather, or piloting) was extra-ordinarily bad, in which case that would be the primary cause.

@RobinBennett "extraordinarly bad" seems subjective. Yet if there is fatalities, at least one and possibly several things extraordinarily bad happened. BTW my point was defining the main or primary or initial cause can be hard (even subjective) as causes can interfere with each other.

I participated in a tiny supporting role in a few crash investigations involving CRJs, so I'll give it a shot, and I would say that when a main cause is listed, especially for something mechanical, it's what you might call a "primary trigger", without which, follow-on supporting factors  and events that led to the crash would never have occurred.  Or an event in a chain that can be considered the "point of no return".
Pilot with poor training takes off in an overloaded airplane, and engine quits after V1/VR and it crashes.  The engine failure will be the main cause, with poor training and overloading added as contributing factors.  Without the engine failure, the poorly trained pilot in his overloaded airplane would've carried on his merry way, so the engine failure can be considered the main cause.
For pure "pilot error" events, it can be more nuanced, with a roughly equal-in-impact chain of events and if you took out any element in the chain, the other elements may have still happened, but just not leading to a fatality.  These reports will often list a series of accident causes without giving critical weight to any one, except to say that the cause was ultimately the crew and not the plane.  Running out of gas is a typical one.
On the other hand, sometimes a crew action is as much a triggering event as a major mechanical failure.  Colgan Flight 3407 is a classic example of this.  The Capt had the Mother of All Brain Farts and pulled when he should have pushed when the shaker went off and this is listed at the main cause.  Now, the shaker went off in the first place because they weren't paying attention to power when the A/P leveled off, but it was the response to the shaker that sealed their fate, and becomes the main cause.
There was a CRJ crash in China caused by taking off with frost on the wings on a cold clear morning.  Frost on the wings was the main cause.  Lack of understanding of the effects of frost, and maybe a bit of normally benign over-rotation-on-takeoff contributed, but without the frost, nothing would have happened.

This is a very interesting point based on your personal experience which I appreciate a lot. I will not mark it as resolved yet hoping that someone else contributes with a different perspective.

No worries.  You'll might get lucky and find someone who has direct experience writing or reviewing Safety Board reports (I provided indirect technical input to my old employer's Product Safety team). If I was still working I could go chat with a Product Safety guy at my old employer and ask directly, but I retired several years ago.


text:
Is the Reynolds number the same for both the airfoil and wing? If not, why/how does it change?
This question might be stupid, but I don't understand this one thing: does the Reynolds number change when you go from the airfoil to the wing? Or is it the same for both?

From the equation that defines it, you can see that its value depends on some properties of the fluid (air), the speed that an object moves through the fluid, and the length of the object.  Nothing else.
For an airplane wing, the length, aka "characteristic linear dimension," is conventionally chosen to be the chord of the wing.  The wingspan doesn't affect the Reynolds number.  Neither does the choice of airfoil.
In other words, given an airfoil (say, a segment in a wind tunnel at a particular chord, airspeed, and air density), and given a wing on an airplane built from the same airfoil with a different chord, airspeed, and air density, the Reynolds numbers for these two situations are likely to be different.


text:
How does p-factor affect jet engines?
How does p-factor affect jet engines, if at all? If it doesn't, why?

@Bianfable I saw that answer before posting up the question, but it’s a little bit vague and does not really address p-factor entirely in my opinion.

Think about what P-factor is and you'll know the answer to this.

@Bianfable there's going to be some P factor in a turbofan, since it's just a fixed pitch prop with oodles of blades, to the extent that flow at the blade AOA varies with body AOA. How much this occurs will be a function of the cowl inlet's efficiency at redirecting the inflow. Downstream guide vanes shouldn't make any difference; it's the asymmetrical lift from differing AOAs of the blades which affects the strength of the downwash from the blades so the fan is making more thrust on one side, just like any propeller. I think there is SOME P factor, but not enough to have a noticeable effect.

@JohnK OK, I retracted my close vote. Feel free to add that as an answer...

This question is relevant and could lead to discussion of gyroscopic effects when pitching (a rapidly rotating) jet engine.

Does this answer your question? Why is rotating engines in opposite directions more important for a propeller-driven plane than a jet?

Since P Factor is primarily variation of AOA of a thrust producing blade when its rotation axis is not aligned with the air stream, you should see some P factor in a turbofan engine, to the extent that the inlet flow strikes the front of the fan from an angle.
I say "some" because the cowl inlet is going to align the inflow to be more perpendicular to the fan face than if the fan was in the freestream (where it becomes just a propeller with lots of extra blades), but it's hard to say how much. In any case, the flow is probably not quite 90 degrees to the fan face at higher body AOA, so it's safe to say there is probably a little bit, but since P factor is not accounted for in turbofan installations, what P Factor exists is not enough to matter (maybe if you stuck a turbofan on the nose of a Cessna 172, you might notice some P Factor effect).
On a turbojet there will be no P Factor at all since the thrust is coming form flow accelerating out the burner can, hot section and tailpipe, not from lift producing propeller/fan blades at the front.

With a turbofan on the nose of a -172, P Factor certainly won't be the only interesting new "effect" that you're suddenly going to notice!

"Maybe" is not an answer.

"Maybe" just jokingly refers to a "turbofan 172".  The answer is, logically there has to be some, but not enough to matter, and "some" might be a 5% effect, or a .5% effect, but in any case it's not enough to matter on aircraft equipped with TFs.